Buggy code:
public class JavaModel extends Openable implements IJavaModel { public static HashSet existingExternalFiles = new HashSet ( ) ; protected JavaModel ( ) throws Error { } protected boolean buildStructure ( OpenableElementInfo info , IProgressMonitor pm , Map newElements , IResource underlyingResource ) throws JavaModelException { } public boolean contains ( IResource resource ) { } public void copy ( IJavaElement [ ] elements , IJavaElement [ ] containers , IJavaElement [ ] siblings , String [ ] renamings , boolean force , IProgressMonitor monitor ) throws JavaModelException { } protected Object createElementInfo ( ) { } public void delete ( IJavaElement [ ] elements , boolean force , IProgressMonitor monitor ) throws JavaModelException { } public boolean equals ( Object o ) { } public IJavaProject findJavaProject ( IProject project ) { } public int getElementType ( ) { } public static void flushExternalFileCache ( ) { } protected IJavaElement getHandleFromMementoForBinaryMembers ( String memento , IPackageFragmentRoot root , int rootEnd , int end ) throws JavaModelException { } protected IPackageFragmentRoot getHandleFromMementoForRoot ( String memento , JavaProject project , int projectEnd , int rootEnd ) { } protected IJavaElement getHandleFromMementoForSourceMembers ( String memento , IPackageFragmentRoot root , int rootEnd , int end , WorkingCopyOwner owner ) throws JavaModelException { } protected IType getHandleFromMementoForSourceType ( String memento , ICompilationUnit cu , int typeStart , int typeEnd ) throws JavaModelException { } public String getHandleMemento ( ) { } protected char getHandleMementoDelimiter ( ) { } public IJavaProject getJavaProject ( String name ) { } public IJavaProject getJavaProject ( IResource resource ) { } public IJavaProject [ ] getJavaProjects ( ) throws JavaModelException { } public Object [ ] getNonJavaResources ( ) throws JavaModelException { } public IJavaProject [ ] getOldJavaProjectsList ( ) throws JavaModelException { } public IPath getPath ( ) { } public IResource getResource ( ) { } public IResource getUnderlyingResource ( ) throws JavaModelException { } public IWorkspace getWorkspace ( ) { } public void move ( IJavaElement [ ] elements , IJavaElement [ ] containers , IJavaElement [ ] siblings , String [ ] renamings , boolean force , IProgressMonitor monitor ) throws JavaModelException { } public void refreshExternalArchives ( IJavaElement [ ] elementsScope , IProgressMonitor monitor ) throws JavaModelException { if ( elementsScope == null ) { elementsScope = new IJavaElement [ ] { this } ; } <START_BUG> JavaModelManager . getJavaModelManager ( ) . deltaProcessor . checkExternalArchiveChanges ( elementsScope , monitor ) ; <END_BUG> } public void rename ( IJavaElement [ ] elements , IJavaElement [ ] destinations , String [ ] renamings , boolean force , IProgressMonitor monitor ) throws JavaModelException { } protected void runOperation ( MultiOperation op , IJavaElement [ ] elements , IJavaElement [ ] siblings , String [ ] renamings , IProgressMonitor monitor ) throws JavaModelException { } protected void toStringInfo ( int tab , StringBuffer buffer , Object info ) { } public static Object getTarget ( IContainer container , IPath path , boolean checkResourceExistence ) { } }

Fix:
JavaModelManager . getJavaModelManager ( ) . getDeltaProcessor ( ) . checkExternalArchiveChanges ( elementsScope , monitor ) ;